Democrats' historic gains position them for unchecked power.

SACRAMENTO — Gov. Jerry Brown and his fellow Democrats are on the cusp of a coveted supermajority in both the Assembly and Senate, giving them the rare power to raise taxes without any Republican support.

No single party has held such a supermajority in Sacramento since 1933.

To cement the dual two-thirds majorities when the Legislature gets down to business next year, Democrats must hold onto one of two Senate seats to be vacated and a few Assembly seats won in tight races. The Senate seats will be filled in special elections expected in March.

The supermajorities would mark a dramatic shift in Sacramento's balance of power, where GOP legislators have aggressively used their ability to block state budget plans and prevent revenue increases to scale back the scope of state government.

Coupled with the approval of Brown's tax plan, Proposition 30, the Democrats now have not only the power but also the money to break free of the deficit that has paralyzed state government for years.

The pressure on Democrats to restore funding for the many services slashed to balance the budget in recent years will be intense.

Already, activists are pressing lawmakers to pump new money into such programs as college scholarships, dental care for the needy and, of course, public schools.

But the first move Brown and legislative leaders made Wednesday was to reassure voters that they would show restraint.

They promised there would be no frenzy of tax hikes.

"Voters have trusted the elected representatives, maybe even trusted me to some extent, and now we've got to meet that trust," Brown said at a Wednesday news conference in the Capitol. "We've got to make sure over the next few years that we pay our bills, we invest in the right programs, but we don't go on any spending binges."

Still, lawmakers can appear to hold the line on revenue generation without actually doing so.

Supermajorities allow lawmakers to impose new fees to pay for infrastructure and other programs that are not technically defined as taxes.

And the same Democrats who are talking tough about fiscal responsibility this week have for years been touting the programs they want to restore or start once the opportunity is there. In addition to raising revenue, they would also be empowered to bring constitutional changes and other measures to voters without any GOP signoff -- and to override gubernatorial vetoes.

Given a supermajority, "We're going to use it," Senate President Darrell Steinberg (D-Sacramento) said Wednesday.

"It will be an awesome responsibility," Steinberg said. "But it's very exciting.''

Steinberg briefed the media on his desire to overhaul the tax code.

The result, he acknowledged, could be more money for the state budget.

Assembly Speaker John A. Perez (D-Los Angeles), who vowed there would be no additional tax increases next year, laid out goals that could trigger more government spending, such as helping students pay for college.

The success Tuesday of Brown's Proposition 30, which raises billions of dollars through temporary income-tax increases on high earners and a quarter-cent surcharge on sales, gives lawmakers breathing room they have not had in years.

With one election, a deficit that has rendered Sacramento dysfunctional and threatened to ravage public schools has been largely wiped out.

Los Angeles Unified School District Supt. John Deasy said in a radio interview Wednesday that the measure's passage provides educators "tremendous hope."

"This stops the floor from dropping out," he said.

The state's finances were given a further boost by a tax measure near the bottom of the ballot, Proposition 39.

Its passage Tuesday raises $1 billion through tax hikes on out-of-state businesses, to be split between a new green building program and the state's general fund.

Erasing all that red ink allows Brown to reboot his governorship.

No longer consumed with living up to his promise to close the deficit, he is free -- at least for now -- to refocus on legacy-building pursuits.

Tuesday's advances for Democrats and their causes were driven, in part, by the popularity of the state's new online registration system, which helped push the number of registered voters above 18 million for the first time.

Those added to the rolls were younger and more likely than ever to be Democrats.

By election day, Republicans had dropped below 30% of the state's electorate for the first time since the state started keeping track in 1922.

And an aggressive, expensive, get-out-the-vote effort by labor unions to beat another ballot measure, Proposition 32, which would have limited their political giving, loomed large.

Democrats unlocked long-held GOP grips in such places as Riverside and Orange counties.